What is momentum?
- Momentum is "mass in motion" (the quantity of motion an object has). All objects have mass; so if an object is moving, then it has momentum. For example, a sports team that's on the move has momentum.
- The amount of momentum an object has depends on 1. how much stuff is moving (mass) and 2. how fast the stuff is moving (velocity). The units are kg*m/s.
Momentum= mass * velocity
p= m*v
- Momentum is a vector quantity (has both magnitude and direction). The direction of the momentum vector is the same as the direction of the velocity vector.
- Objects have a large momentum if the mass, velocity, or both are large Check Your Understanding:
1.) Determine momentum
a. p=(60)*(9)= 540 kg*m/s, east
b. p=(1000)*(20)=20,000 kg*m/s, north
c. p=(40)(*(2)= 80 kg*m/s, south
2.) Momentum is 20,000 units; what would be the new momentum if
a. p=2(20,000)= 40,000 units
b. p=3(20,000)= 60,000 units
c. p=2(20,000)= 40,000 units
d. p=4(20,000)= 80,000 units
3.) Compare the velocities of these 3 players. Which player has the greatest momentum? Explain. The tight end goes 2 times the amount of the lineman, but in the same amount of time (he's twice as fast- moves 6m/s.. The halfback goes 3 times as far as the lineman, in the same amount of time, so his velocity is 9 m/s. The halfback and the tight end both have the greatest momentum; each of theirs is 540 kg*m/s, whereas the lineman only has a momentum of 360 kg*m/s.
Lesson 1b:
What is the connection between momentum and the impulse connection?
- An object with momentum is hard to stop
- Impulse is the change in momentum
- A rebound is a special type of collision involving a direction change- the result is a large change in velocity
Lesson 1c:
What are some of the real-world applications?
- when objects bounce off each other, this is called rebounding; it involves a change in direction (of an object).
- crumple zones on cars are made to reduce the effect of the force (bigger the collision time, less effect of force).
- example: mountain climbers use ropes to increase stopping time and decrease effect of the stopping force.
Lesson 2d:
What equations can be used for algebraic problem soling of momentum conservation in collisions?
- Split the collision into "before" and "after"
- Solve for the momentum in each (of both objects) and add them up to get the total momentum
Lesson 2e:
What are momentum conservation in explosions?
- In an explosion, an internal impulse acts in order to propel the parts of a system into a variety of directions
- After the explosion, the individual parts of the system have momentum
Table of Contents
Chapter 7: Momentum
Lesson 1a: Momentum
What is momentum?- Momentum is "mass in motion" (the quantity of motion an object has). All objects have mass; so if an object is moving, then it has momentum. For example, a sports team that's on the move has momentum.
- The amount of momentum an object has depends on 1. how much stuff is moving (mass) and 2. how fast the stuff is moving (velocity). The units are kg*m/s.
Momentum= mass * velocity
p= m*v
- Momentum is a vector quantity (has both magnitude and direction). The direction of the momentum vector is the same as the direction of the velocity vector.
- Objects have a large momentum if the mass, velocity, or both are large
Check Your Understanding:
1.) Determine momentum
a. p=(60)*(9)= 540 kg*m/s, east
b. p=(1000)*(20)=20,000 kg*m/s, north
c. p=(40)(*(2)= 80 kg*m/s, south
2.) Momentum is 20,000 units; what would be the new momentum if
a. p=2(20,000)= 40,000 units
b. p=3(20,000)= 60,000 units
c. p=2(20,000)= 40,000 units
d. p=4(20,000)= 80,000 units
3.) Compare the velocities of these 3 players. Which player has the greatest momentum? Explain.
The tight end goes 2 times the amount of the lineman, but in the same amount of time (he's twice as fast- moves 6m/s.. The halfback goes 3 times as far as the lineman, in the same amount of time, so his velocity is 9 m/s. The halfback and the tight end both have the greatest momentum; each of theirs is 540 kg*m/s, whereas the lineman only has a momentum of 360 kg*m/s.
Lesson 1b:
What is the connection between momentum and the impulse connection?- An object with momentum is hard to stop
- Impulse is the change in momentum
- A rebound is a special type of collision involving a direction change- the result is a large change in velocity
Lesson 1c:
What are some of the real-world applications?- when objects bounce off each other, this is called rebounding; it involves a change in direction (of an object).
- crumple zones on cars are made to reduce the effect of the force (bigger the collision time, less effect of force).
- example: mountain climbers use ropes to increase stopping time and decrease effect of the stopping force.
Lesson 2d:
What equations can be used for algebraic problem soling of momentum conservation in collisions?- Split the collision into "before" and "after"
- Solve for the momentum in each (of both objects) and add them up to get the total momentum
Lesson 2e:
What are momentum conservation in explosions?- In an explosion, an internal impulse acts in order to propel the parts of a system into a variety of directions
- After the explosion, the individual parts of the system have momentum